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oe1(光电查) - 科学论文

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出版时间
  • 2019
  • 2018
研究主题
  • microwave photonics
  • interdigital resonator
  • microwave gas sensor
  • PSE-coated
  • microwave photonic mixer
  • analog optical signal processing
  • phase shift
  • photonic array antenna
  • gain
  • integrate
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • Inner Mongolia University
  • Jinan University
  • King Mongkut’s University of Technology North Bangkok
  • Beijing University of Posts and Telecommunications
  • Wroclaw University of Technology
  • Rajamangala University of Technology Suvarnabhumi
  • Southern University of Science and Technology
  • Charles Darwin University
  • University of Ottawa
  • University of Kent
508 条数据
?? 中文（中国） ▾

  • Hybrid Ligand Exchange of Cu(In,Ga)S <sub/>2</sub> Nanoparticles for Carbon Impurity Removal in Solution Processed Photovoltaics

    摘要： The solution processing of Cu(In,Ga)(S,Se)2 photovoltaics from colloidal nanoparticles has long suffered from deleterious carbonaceous residues originating from long chain native ligands. This impurity carbon has been observed to hinder grain formation during selenization and leave a discrete residue layer between the absorber layer and the back contact. In this work, organic and inorganic ligand exchanges were investigated to remove tightly bound native oleylamine ligands from Cu(In,Ga)S2 nanoparticles, thereby removing the source of carbon contamination. However, incomplete ligand removal, poor colloidal stability, and/or selective metal etching was observed for these methods. As such, an exhaustive hybrid organic/inorganic ligand exchange was developed to bypass the limitations of individual methods. A combination of microwave-assisted solvothermal pyridine ligand stripping followed by inorganic capping with diammonium sulfide was developed and yielded greater than 98% removal of native ligands via a rapid process. Despite the aggressive ligand removal, the nanoparticle stoichiometry remained largely unaffected when making use of the hybrid ligand exchange. Furthermore, highly stable colloidal ink formulations using non-toxic dimethyl sulfoxide were developed, supporting stable nanoparticle mass concentrations exceeding 200 mg/mL. Scalable blade coating of the ligand exchanged nanoparticle inks yielded remarkably smooth and microcrack free films with RMS roughness less than 7 nm. Selenization of ligand exchanged nanoparticle films afforded substantially improved grain growth as compared to conventional non-ligand exchanged methods yielding an absolute improvement in device efficiency of 2.8%. Hybrid ligand exchange nanoparticle based devices reached total-area power conversion efficiencies of 12.0%, demonstrating the feasibility and promise of ligand exchanged colloidal nanoparticles for the solution processing of Cu(In,Ga)(S,Se)2 photovoltaics.

    关键词： hybrid ligand exchange,blade coating,diammonium sulfide,carbon impurity removal,photovoltaics,grain growth,Cu(In,Ga)(S,Se)2,solution processing,ligand exchange,selenization,microwave-assisted solvothermal,colloidal nanoparticles,device efficiency

    更新于2025-09-23 15:21:01

  • How the Mixed Cations (Guanidium, Formamidinium, and Phenylethylamine) in Tin Iodide Perovskites Affect Their Charge Carrier Dynamics and Solar Cell Characteristics

    摘要： Despite recent interest in lead-free Sn iodide perovskite (ASnI3) solar cells, the role of mixed A-site cations is yet to be fully understood. Here, we report the effect of the ternary mixing of organic A-site cations (guanidium, GA; formamidinium, FA; and phenylethylamine, PEA) on the solar cell performance and charge carrier dynamics that are evaluated using time-resolved microwave conductivity (TRMC). (GAxFA1?x)0.9PEA0.1SnI3 exhibits the maximum power conversion efficiency (PCE) of 7.90% at x = 0.15 and a drastic decrease with increasing GA content. Notably, our TRMC measurements of ASnI3 with/without a hole transport layer reveal the same trend with the devices. From the analyses, we suggest that a variation of electron mobility affected by the location of the GA cation in the grains significantly impacts the PCE. Our work sheds light on the role of mixed A-site cations and directs a route toward the further development of Sn perovskite solar cells.

    关键词： time-resolved microwave conductivity,mixed A-site cations,solar cell performance,Sn iodide perovskite,charge carrier dynamics,lead-free

    更新于2025-09-23 15:21:01

  • Synthesis of Calcium Aluminate-Based Luminophores by the Citrate Nitrate Sol–Gel Process

    摘要： Microwave-assisted sol–gel process was used to synthesize calcium aluminate and luminescent materials based on it, which find wide use in the manufacture of construction materials, catalysts, optical emission sources, and display devices. The major processes involved in the formation of crystalline calcium aluminate were identified resorting to powder X-ray diffraction, thermal analysis, scanning electron microscopy, and IR spectroscopy data. Synthetic steps have moderate activation energies in the 44–260 kJ/mol range. Luminescence characteristics of the obtained crystal phosphors were measured. The increase in the synthesis temperature to 1200°C and the increase in the activator concentration to 5 mol % enhance the luminescence of the Eu3+-activated calcium aluminate-based luminophore. Further increase in the concentration of the activator ions leads to luminescence quenching caused by the concentration effect.

    关键词： calcium aluminate,sol–gel process,microwave treatment,europium(III) ions,crystal phosphor

    更新于2025-09-23 15:21:01

  • Broadband Cognitive Radio Enabled by Photonics

    摘要： Cognitive radio is considered as a possible disruptive force to improve the spectral resource efficiency through sensing and interacting with the environment. Traditional electrical technologies to implement the cognitive radio face challenges in terms of bandwidth, resolution, and speed. In this paper, the concept and architecture of broadband cognitive radio systems enabled by photonics are proposed. Key microwave photonic techniques for the architecture are reviewed, including the photonics-based spectrum sensing, the photonic arbitrary waveform generation, the photonics-based self-interference cancellation processing, and the microwave photonic dechirp processing and radar imaging. A preliminary demonstration of a cognitive radar system enabled by photonics is performed. The future possible research directions on this topic are discussed.

    关键词： Cognitive radio,spectrum sensing,microwave photonics,radar imaging,self-interference cancellation,waveform generation

    更新于2025-09-23 15:21:01

  • PERFORMANCE IMPROVEMENT OF PATCH ANTENNA USING CIRCULAR SPLIT RING RESONATORS AND THIN WIRES EMPLOYING METAMATERIALS LENS

    摘要： In this paper, the left-handed metamaterial which acts as a lens is employed to improve the performance of a microstrip patch antenna. The left-handed metamaterial used in this work is a three-dimensional periodic structure which consists of circular split ring resonators and thin wires. The three-dimensional periodic metamaterial structure shows angular independency characteristics in wide range angles, so it acts as a metamaterial lens. However, the MTM structure in?nite periodicity truncation has no impacts on the MTM lens scattering, e?ective parameters and homogeneity. The left-handed metamaterial is placed in front of the microstrip patch antenna and due to the negative refractive index property of the left-handed metamaterial; the radiated electromagnetic beam size decreases which results in a highly focused beam. The proposed antenna has been designed and simulated using CST microwave studio, and the metamaterial e?ective parameters are extracted from the S parameters by using Nicolson-Ross-Weir algorithm and by selecting the appropriate ambiguity branch parameter. Furthermore, the angular independency of the metamaterial lens has been veri?ed by rotating the metamaterial structure with respect to the excitation probe of the transverse electromagnetic waves and extracting the S-parameters and the e?ective parameters for each rotation angle. A parametric analysis has been performed to study the e?ects of the patch antenna and left-handed metamaterial lens separation and the size of the three-dimensional left-handed metamaterial structure on the radiating properties and the impedance matching of the proposed antenna. For the experimental veri?cation, the proposed antenna operating at 10 GHz is fabricated; the return loss, radiation pattern and gain for the proposed antenna with and without metamaterial are measured. Furthermore, the results show that the antenna gain is improved by 4.6 dB which validates the concept of beam focusing using negative refractive index metamaterial structure, while the return loss and bandwidth are slightly reduced. The simulation and experiment investigated the idea of the beam focusing using negative refractive index metamaterial lens in microwave regime.

    关键词： microstrip patch antenna,CST microwave studio,beam focusing,Nicolson-Ross-Weir algorithm,parametric analysis,left-handed metamaterial,circular split ring resonators,negative refractive index,angular independency,experimental verification,thin wires

    更新于2025-09-23 15:21:01

  • Commercially Fabricated Antenna-Coupled Transition Edge Sensor Bolometer Detectors for Next-Generation Cosmic Microwave Background Polarimetry Experiment

    摘要： We report on the development of commercially fabricated multi-chronic antenna-coupled transition edge sensor (TES) bolometer arrays for cosmic microwave background (CMB) polarimetry experiments. The orders of magnitude increase in detector count for next-generation CMB experiments require a new approach in detector wafer production to increase fabrication throughput. We describe collaborative efforts with a commercial superconductor electronics fabrication facility (SeeQC, Inc.) to fabricate antenna-coupled TES bolometer detectors. We have successfully fabricated an operational dual-polarization, dichroic sinuous antenna-coupled TES detector array on a 150-mm-diameter wafer. The fabricated detector arrays have average yield of 95% and excellent uniformity across the wafer. Both RF characteristics and TES bolometer properties are suitable for CMB observations. We successfully fabricated different types of TES bolometers optimized for frequency multiplexing readout, time-domain multiplexing readout, and microwave SQUID multiplexing readout. We also demonstrated high production throughput. We discuss the motivation, design considerations, fabrication processes, test results, and how industrial detector fabrication could be a path to fabricate hundreds of detector wafers for future CMB polarimetry experiments.

    关键词： TES bolometer,Fabrication,Cosmic Microwave Background,Technology transfer

    更新于2025-09-23 15:21:01

  • Fabrication of OMT-Coupled Kinetic Inductance Detector for CMB Detection

    摘要： Future cosmic microwave background (CMB) experiments, including the large scale ground-based Stage Four CMB Experiment (CMB-S4), satellites, and balloons, aim to map the CMB to an unprecedented precision in order to answer several key questions in cosmology. However, to reach the target noise sensitivity, more than 100,000 detectors will be needed. Arrays of kinetic inductance detectors (KIDs) are a promising alternative for experiments that require large number of detectors due to the intrinsic multiplexing capabilities. We present the fabrication procedure for a prototype planar orthomode transducer (OMT)-coupled multi-color KID array optimized for 220/270 GHz frequency bands. These devices are made from silicon-on-insulator wafers to provide a low-loss substrate for the KIDs. The OMT couples the two polarizations of light from a wide-band feedhorn to separate Nb/SiN/Nb microstrip lines, which are then coupled to Al/Nb lumped-element KIDs (LEKIDs). The silicon on the backside of the OMT is etched away using deep reactive ion etch to release the OMT membrane to enable operation over a wide bandwidth. Finally, the buried oxide is removed underneath the KID capacitors in order to minimize two-level system noise and loss mitigation. We achieved a good yield (> 80%) on our prototype devices.

    关键词： Kinetic inductance detector,Fabrication,Cosmic microwave background

    更新于2025-09-23 15:21:01

  • Particle Response of Antenna-Coupled TES Arrays: Results from SPIDER??and the Laboratory

    摘要： Future mm-wave and sub-mm space missions will employ large arrays of multi-plexed transition-edge-sensor (TES) bolometers. Such instruments must contend with the high flux of cosmic rays beyond our atmosphere that induce ‘glitches’ in bolometer data, which posed a challenge to data analysis from the Planck bolom-eters. Future instruments will face the additional challenges of shared substrate wafers and multiplexed readout wiring. In this work, we explore the susceptibility of modern TES arrays to the cosmic ray environment of space using two data sets: the 2015 long-duration balloon flight of the SPIDER?cosmic microwave background polarimeter, and a laboratory exposure of SPIDER? flight hardware to radioactive sources. We find manageable glitch rates and short glitch durations, leading to mini-mal effect on SPIDER? analysis. We constrain energy propagation within the sub-strate through a study of multi-detector coincidences and give a preliminary look at pulse shapes in laboratory data.

    关键词： Cosmic microwave background,Cosmic ray,Bolometer,Transition-edge sensor

    更新于2025-09-23 15:21:01

  • Pumping Systems for Compton Free-Electron Lasers: Microwave Undulators and Powering Sources

    摘要： The concept of Compton-type free-electron lasers (FELs) operating in short wavelength ranges with a high e?ciency and power level is currently underway at the IAP RAS (Nizhny Novgorod). This concept is aimed at reducing the energy of a driving relativistic electron beam and thereby increasing the e?ciency of the electron–wave interaction in FELs, as well as making the oscillator relatively compact. The basis of this concept is microwave undulators of a new type — the so-called “?ying” undulators. This paper is devoted to the results of the current studies of these undulators, their simulation, and “cold” electrodynamic tests in the Ka band. For powering microwave undulators, a spatially extended narrow-band ˇCerenkov surface-wave oscillators (SWOs) are developed in the speci?ed frequency range driven by Sinus-6, a high-current accelerator, with a particle energy of 0.5 MeV, a current of 5 kA, and a pulse duration of 25 ns. The required sub-gigawatt power level of output radiation combined with a high stability of the narrow-band oscillation regime is achieved under conditions of a strongly oversized oscillator by using two-dimensional distributed feedback provided in a 2D doubly-periodic slow-wave structure. The design parameters of a 32 GHz/0.5 GW SWO intended for powering microwave undulators are presented and the results of its simulation and reported.

    关键词： flying undulators,Ka band,Cerenkov surface-wave oscillators,Sinus-6 accelerator,microwave undulators,Compton-type free-electron lasers

    更新于2025-09-23 15:21:01

  • Spatial Retrieval of Broadband Dielectric Spectra

    摘要： A broadband soil dielectric spectra retrieval approach (1 MHz–2 GHz) has been implemented for a layered half space. The inversion kernel consists of a two-port transmission line forward model in the frequency domain and a constitutive material equation based on a power law soil mixture rule (Complex Refractive Index Model—CRIM). The spatially-distributed retrieval of broadband dielectric spectra was achieved with a global optimization approach based on a Shuffled Complex Evolution (SCE) algorithm using the full set of the scattering parameters. For each layer, the broadband dielectric spectra were retrieved with the corresponding parameters thickness, porosity, water saturation and electrical conductivity of the aqueous pore solution. For the validation of the approach, a coaxial transmission line cell measured with a network analyzer was used. The possibilities and limitations of the inverse parameter estimation were numerically analyzed in four scenarios. Expected and retrieved layer thicknesses, soil properties and broadband dielectric spectra in each scenario were in reasonable agreement. Hence, the model is suitable for an estimation of in-homogeneous material parameter distributions. Moreover, the proposed frequency domain approach allows an automatic adaptation of layer number and thickness or regular grids in time and/or space.

    关键词： soil measurements,electromagnetic scattering inverse problems,dielectric measurements,modeling,microwave propagation,dielectric materials

    更新于2025-09-23 15:21:01